1. Field of Invention
The invention relates to packing media and particularly to hollow open ended plastic packing elements for fluid-fluid and liquid-gas contact apparatus.
2. Description of the Prior Art
Heretofore, various forms and sizes of packing elements which may be orderly stacked or randomly dumped and are self orienting have been proposed for mass transfer between two counter flowing fluids such as a liquid and a gas and through which the liquid flows by gravity and contacted by the upwardly flowing gas.
Such plastic packing elements are disclosed in U.S Pat. Nos. 3,506,248; 3,914,351; 4,122,011 and 4,195,043.
In many industrial applications, it is necessary to provide large fluid-fluid interfacial area, as well as adequate agitation in both phases, to facilitate mass transfer and/or heat transfer operations. Vessels with high-void packings are commonly used to accomplish such fluid-fluid contact and packed bed adsorption or distillation towers are examples of gas-liquid contact devices.
For efficient operation of heat and/or mass transfer in a manufacturing/processing environment, gas and liquid are usually brought into contact with each other in a counter-current fashion, with liquid flowing downward and gas flowing upward in the packed bed. Packings may have either an ordered or random geometrical arrangement. The random packings are most popular due to their low cost and the ease of installation. A random packing is composed of large numbers of individual packing elements, which are randomly dumped into a vessel to form a packing structure.
"Packing Element" is the preferred term for identical individual structural parts, from which a packed bed can be formed. The present invention contemplates designs of packing elements which will when randomly dumped or orderly stacked to form a packed bed, provide better fluid-fluid contact than the packed beds made of prior art packing elements.
In a high-void structural packing, the mechanisms of liquid flow is interstice intermittent surface-droplet flow at low liquid flow rate, gradually becomes interstice continuous-rivulet flow at moderate liquid flow rate, and finally becomes film/dripping flow at high liquid flow rate. The number of interstices per unit volume strongly influences the liquid hold up, liquid phase mixing rate, as well as gas-liquid interfacial area. In the prior art random packings, the interstices are formed by packing element-to-packing element contacts. In the present invention, the number density of interstices is greatly increased by designing interstices into packing elements. Those intra-element interstices have the same function as inter-element interstices.